Answer:
a. (3-7x) + (3-7x) + (3-7x) + (3-7x)
b. 4(3-7x)
c. 12 - 28x
Step-by-step explanation:
To find the perimeter of a square, you need to add up all the sides
a. Since a square has all equal sides you will need to write the expression four times: (3-7x) + (3-7x) + (3-7x) + (3-7x) = perimeter
b. Expressing this as a product, we can condense the formula to 4 multiplied by the expression since it is written four times: 4(3-7x) = perimeter
c. Using the distributive property, we can write the product 4(3-7x) from b. as: (4)(3) + (4)(-7x) = 12 + (-28x) = 12 - 28x = perimeter
Easy way, visual
50---68---80%
Difference 18 12
Invert order to give ratio of 50% and 80%
Ratio 12 18 = 2:3
So by simple proportion:
volume of 50% needed = 100*2/(2+3)=40 mL
volume of 80% needed = 100*3/(2+3)=60 mL
Algebra way
Let x=volume of 50% needed.
Then
0.50*x+0.80*(100-x) = 0.68(100)
Expand and solve for x
0.5x+80-0.8x = 68
0.8x-0.5x = 80-68
0.3x = 12
x=12/0.3 = 40 mL (volume of 50%)
100-x=100-40=60 mL (volume of 80%)
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