What is the meaning of the expression 5 x (100 - 25)?

This is geometry. could anyone ? i can't fail this class. my grade is quite low already.

Give the equations of two different lines that are perpendicular to the line 3x + 4y = 7.

Eliza wants to make $10,000 from her investments. she finds an investment account that earns 4.5% interest. she decides to deposit $2,500 into an account. how much money will be in her account after 14 years?