7c-70 is the Answer
first you want to do distributive property. since the -10 is on the outside of the parentheses, you multiply it by the numbers that are in the parentheses. After you do this, the equation should look like
50c-40c-70-3c
Then, you want to combine like terms. The 70 does not have a variable so you want to combine the one with exponents which are 50c,-40, and 3c
50-40 is 10. Then you would add the variable: 10c 10c-3c is 7c once all like terms are combined the equation should look like this:
7c-70
I really hope this helped you
