the answer would be a=3. to put it more clear, multiply the number outside of the parenthesis. so for example 4•2a is 8a, and 4•-1 is -4. since the -4 has no variable, it would just be 8a-4. next, the -10 times a positive a would be -10a. a positive times a negative is negative. next, do -10•-5 which is positive 50. remember, a negative times a negative is positive! after this, take the 8a-4=-10a+50 and add the constant and the variable (-10a) by the 8a. ALWAYS go right to left when subtracting or adding. you should get 18a. so 18a-4=50. take the negative four and add a positive four because you need to make the sides equal, add the four to 50, and you should get 18a=54. lastly, 54/18 is 3! so, A=3