Help please with explanation (I’m being timed)

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²

Ageologist had two rocks on a scale that weighed 4.6 kilograms together.rock a was 0.5 of the total weight.how much did rock a weigh?

Evaluate 3(a + b + c)squared for a = 2, b = 3, and c = 4. a. 54 b. 243 c.729 add solution .