What is the solution to the equation 21^x + 3 = 14?

The average human heart beats 72 beats per minute. how many times does it beat in 15 seconds?

Prove that 3: 8 is equivalent to 12: 32.a. use diagrams to support your answer.

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?