To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

8a⁴ - 5a⁴ = 3a⁴

The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 11cm + 5cm + 13cm = 29cm

You need to find the value of b so solve the first equation in terms of y:

b + y = 9
y = 9 - b

then substitute the result (9 - 1b) into the second equation:

-6b - 9(9 - b) = -3
-6b + (-9 x 9) + (-9 x -b) = -3
-6b - 81 + 9b = -3
-6b + 9b = -3 + 81
3b = 78
b = \( \frac{78}{3} \)
b = 26

A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r²h and the surface area is 2(π r²) + 2π rh.

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

7c(c - x)
7(3)(3 - 1)
7(3)(2)
(21)(2)
42