Math !
part a) write an expression that represents the following expression using the variable b. "billy's age in 8 years."
part b.) write and equation using the expression above if in 8 years billy will be 21 years old.
part c.) how old is billy now?
part d.) write and solve a word problem that matches the equation a- 6=10

If b is Billy's age *now*, part A would look something like this:

b + 8

Usually, it looks a little more like x = b + 8, just because we like setting the equation to an unknown variable (usually x).

b + 8 = 21

To simplify the above equation, subtract 8 from both sides:

b = 21 - 8
OR
b = 13

We just found the answer to part C above.

I'm not going to work out part D for you (you got this), but use the subtraction sign to your benefit and replace it with a word like "ago", if you're choosing age as your word problem. You could also do the traditional candy word problem where you once had 10 jellybeans and now you have 6 Up to you. "A" will be your "now" in that case. Have fun!