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7th grade Math review

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John needs to be at school by 8:00 am. It takes 20 minutes to walk to school, 10 minutes to eat breakfast, and 20 minutes to get ready. What time does he need to get up in order to make it to school and not be tardy?
Add together the 20 minutes, 10 minutes, and 20 minutes. Subtract the minutes from 8:00 am. 7:10 pm
x-6=-1
Add 6 to both sides. Solve for x. x=5
3.4y=17
Divide both sides by 3.4 to solve for y. y=5
I have a cube-shaped box with sides of length 6 feet. What is the volume in feet? What is the volume in inches?
length x width x height is 6x6x6=volume in feet. 12 inches on a foot, so 6 x 12 to get one side in inches, then that number (72)x(72)x(72) to get cubic inches, In feet, 216 cubic feet, in inches 373,248 cubic inches
What is 30% of 210?
Change 30% to a decimal 0.3, then multiply 0.3 times 210. 63
What percent of 15 is 3?
Divide 3 by 15, then change to percent. 0.2 becomes 20%
Find the percent of change from 75 to 100. Is this a decrease or an increase?
NEW-ORIGINAL /ORIGINAL. 100-75/100=25/100=25% increase.
Sally bought a new dress that cost $30. There is 8% sales tax. What is the total cost?
Change 8% to decimal 0.08, multiply the cost of dress by 0.08, $2.40. Add the tax to the cost of the dress. $30.00+$2.40=$32.40.
If there are 325 rabbits and 175 of them are black, what if the ratio of black rabbits to all rabbits?
175/325= 7/13
n/8=3/24. What is n?
Cross multiply. 3 times 8 divided by 8=1
6/10=8/n What is n?
Cross multiply. 8 times 10 divided by 6=13.3
What is the volume of a rectangular prism that is 3 by 4 by 5 feet?
Multiply length times width times height. 3x4x5=60 cubic feet
What is the volume of a triangular prism with a base that has area 12.5 square meters and a height of 9 meters?
Take the area of the base times the height. 12.5x9=112.5 cubic meters
What is the surface area of a rectangular prism that has width 4 inches, length 6 inches, and height 8 inches?
You have 6 faces to find, and they are in pairs, so 2(4x6), 2(6x8), and 2(4x8). Then add together. 48 plus 96 plus 64=208 square inches
What is the surface area of a pyramid with a square base with sides 6 inches and a height of 8 inches, without the base?
You have 4 triangles to find. base times height divided by 2.So, 6 x 8 /2=24. There are 4, so 4 x 24=96 square inches.
If 35% of the flowers are blue, and there are 280 flowers, how many are blue?
Change 35% to decimal 0.35, multiply by 280. 0.35 x 280- 98
6q-15=81. What is q?
Add 15 to both sides. 6q=81plus 15=96. Divide both sides by 6. 96/6=16