Page 131 - Math Course 3 (Book 1)

Direct Variation Equation

Write a direct variation equation that relates x and y. Assume that y varies directly as x. Then solve.

4. If y = –8 when x = –2, find x 5. If y = 45 when x = 15, find x
when y 32. when y = 15.

6. If y = –4 when x = 2, find y 7. If y = –9 when x = 3, find y
when x = 6. when x = –5.

8. If y = 4 when x = 16, find y 9. If y = 12 when x = 18, find x
when x = 6. when y = –16.

Write a direct variation equation that relates the variables. Then graph the equation.

10. TRAVEL The total cost C of gasoline is $1.80 times the number of gallons g.

Gasoline Cost
C

28

24

20
Cost($) 16

12

8

4

0 2 4 6 8 10 12 14 g
Gallons

123