Combine like terms .Plez Halp TnT

A. 7a + 70 - 13 a - 1 lb

B. -5a - 12a + 2b - 3b

You can ride your bike around your block 6 times and the whole neighborhood 5 times in 16 minutes. you can ride your bike around your block 3 times and the whole neighborhood 10 times in 23 minutes. how long does it take you to ride around the neighborhood?

What is the solution to the system of equations? y=1.5-3 y=-x

How much is $1200 worth at the end of1 year,if the interest rate is 5.5% is compounded quarterly.