Step-by-step explanation:
You are finding the whole
0.7 × 20 = 14
or
70% of 20 = 7/10 x 20 = 7/10 x 20/1 = 140/10
140/10
140/10 = 14/1
The minimum number of questions he need to do are 14
I'm not sure if you are finding the part or the whole
let me know if im wrong
2/3 6/9 9/12 are three fractions with different numerator
First, we compute the highest common factor between the numbers of toys. The highest common factor for 45, 105 and 75 is 15. Therefore, we will need 15 shelves. On each shelf, there will be 45/15 = 3 dolls, 105/15 = 7 footballs and 75/15 = 5 small cars

So y=2x is the only answer that fit y=kx, while k=2
2x + 3(8 - 3x) = 3
2x + 24 -9x = 3
-7x = -21
x = 3
y = 8 - 3x
y = 8 - 3(3)
y = 8-9
y = -1
Check the math:
2(3) + 3(-1) = 6 - 3 = 3