Solve the systems by the addition method: {2x+y= -1 x-2y= -4

A) to solve for r, divide both sides by t.

R = d/t

B) divide total feet swam by time:

665,280 feet / 3 hours = 221,760 feet per hour

C) 1 mile = 5,280 feet. Divide feet per hour by 5280:

221,760/5280 = 42 miles per hour

D) long distances are usually calculated in miles because it’s smaller numbers which are easier to use in calculations.