Help me pleas: Find the value of a and b when x=10

a = 5x (squared) ÷ 2

b = 2x (squared) (x-5) ÷ 10x

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Mustafa contributes 11% of his $67,200 annual salary to his 401k plan. what is his pretax income

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.