What is The ratio of 20 hours to 45 hours

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36

Which function has an inverse function? a.f(x)= |x+3|/5 b. f(x)= x^5-3 c. f(x)= x^4/7+27 d. f(x)= 1/x²

Alexandra drove from michigan to colorado to visit her friend. the speed limit on the highway is 70 miles per hour. if alexandra's combined driving time for the trip was 14 hours how many miles did alejandra drive?