The product of a number and twelve is 36

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Given f(x)= 9x+1 and g(x)=x^3, choose the expression (f*g)(x)

Lizette is training for a marathon. at 7: 00 she left her house and ran until 8: 30, then she walked until 11: 30. she covered a total distance of 18 miles. her running speed was six miles per hour faster than her walking speed. find her running and walking speeds in miles per hour.