-5 + a = -10
how do i solve for a??

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Select the correct answer from each drop-down menu. consider the following polynomials equations. 3x^2(x-1) and -3x^3+ 4x^2-2x+1 perform each operation and determine if the result is a polynomial. is the result of a + b a polynomial? yes or no is the result of a - b a polynomial? yes or no is the result of a · b a polynomial? yes or no

What is the period of the sinusoidal function ?