Use a variable for the unknown number so it would be 77-2x also if you don't know a number and a variable together means to multiply them
Assuming that Anita needs hollow right circular cones, we are solving for its lateral surface area, which is given by the formula πr√(h²+r²), where r is the radius and h is the height.
r = 6 ft / 2 = 3 ft
Solving for the lateral surface area of one cone:
LSA = (3.14) (3) [√(12²+3²)] = 116.52 sq ft.
Since she needs 10 cones:
10 * 116.52 sq. ft = 1,165.2 sq ft.
She will need 1,165.2 sq ft of material.
Multiply the coefficients and the powers of 10 with each other:

The numeric part simply yields

As for the powers of 10, you have to add the exponents, using the rule

So, we have

So, the final answer is

You have to add the numbers that have like terms together. For example you would add the 14 y and the -134y and get -120y and then you would add the 112, 2, and the -12 and get a 102
So your answer would be -120y+102