What is the solution for c given equation 3/4c-11=13?

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 25, a standard deviation of 2.5, and margin of error of 5%

X+y=-4 x-y=2 use elimination with adding and subtraction