Please help solve the problems and show how you solved them

26-4s=9s

-3r+10=15r-8

-9(t-2)=4(t-15)

Astore sells two types of radios. one type sells $87 and the other for $119. if 25 were sold and the sales were $2495, how many of the $87 radios were sold a) 5 b) 20 c) 15 d)10

Twenty points. suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?