The engines changes up and down motion into rotary motion

In priyas math class there are 10 boys and 15 girls. what is the ratio of boys to girls in priyas math class? express your answer as a decimal

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

Use sigma notation to represent the following series for 9 terms.