The difference between 5 times a number and 3 is 12

If a 36 inch yardstick casts a 21 foot shadow, how tall is a building whose shadow is 168 feet? what is the scale factor

Can someone tell me if this is perpendicular? !

The average daily maximum temperature for laura’s hometown can be modeled by the function f(x)=4.5sin(πx/6)+11.8 , where f(x) is the temperature in °c and x is the month. x = 0 corresponds to january.what is the average daily maximum temperature in may? round to the nearest tenth of a degree if needed.use 3.14 for π .