If y varies directly as x, and x =9 when y =15, Find y when x =21

y = x

15 = 9

y = 21

9y = 315

y = 315/9

y = 35

35

Step-by-step explanation:

y is propotional to x, means, if x changes, y changes.

Considering, y depends on x only. Introduce a constant.

y = kx

When x = 9, y = 15,

=> 15 = k(9) => 5/3 = k

When x = 21, note that k is constant.

=> y = kx = (5/3)*21

= 35

square pyramid

step-by-step explanation:

square prism looks like nothing like that

triangular prism has a rectangular base instead of a square base

tetrahedron has a triangular base

answer:   expression= p+p*d%

price reduction + sale price = $625

sale price: $p+$p*d%

where d% is the percentage of discount

step-by-step explanation:

original price = p

price went down by $150 price reduction $p*d%

sale price= $ 475

therefore the price before sale is: $625

and the expression that shows the price before sale is: p+p*d%