Solve. 4/7 = 21/ x - 3a. x = 15b. x = 94c. x = 39 3/4d. x = 12 3/7

4/7 = 21/ (x - 3)

multiply by (x-3) on each side

4(x-3)/7 =21

multiply by 7 on each side

4(x-3) = 21*7

distribute

4x-12 = 147

add 12 to each side

4x = 159

divide by 4

x = 159/4

change back to a mixed number

4 goes into 159 39 times with 3 left over

39 3/4

Choice C

i think this could be a possible answer (1 / 84) -1

good luck! : d

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15