Evaluate the equation 7C3

Are carpet coast $15 per square metre. the total delivery charge is $21 peter buys n squared metres of carpet what is the expression which represents the total cost in $

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

The ratios of boys to girls on a soccer league is 2: 5. if there are 28 boys, how many girls are playing soccer? extra points! will mark as brainiest asap