If y is directly proportional to x and y = 17.5 when x=21 find y when x=39

direct proportion y=kx , k is constant and k does not equal to 0.

17.5=k(21)

k=5/6

when x =39

y=5/6 ×39

y=32.5

21 = 39

—. —

17.5 Y

21y= 682.5

Y=32.5

ANOTHER WAY TO SOLVE IT IS...

Y=kx

17.5=k*21

.833=k

S

Y=kx

Y=.833*39

Y=32.5

f(x) = y

f(-3) = -5

step-by-step explanation:

example 2 – simplify: step 1: completely factor both the numerators and denominators of all fractions. step 2: change the division sign to a multiplication sign and flip (or reciprocate) the fraction after the division sign; essential you need to multiply by the reciprocal. step 3 : cancel or reduce the fractions.