To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(7a)(2ab) + (4a²)(2b)
(7 x 2)(a x a x b) + (4 x 2)(a² x b)
(14)(a¹⁺¹ x b) + (8)(a²b)
14a²b + 8a²b
22a²b

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

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

7b + y = 2
y = 2 - 7b

then substitute the result (2 - 7b) into the second equation:

-8b + 1(2 - 7b) = 3
-8b + (1 x 2) + (1 x -7b) = 3
-8b + 2 - 7b = 3
-8b - 7b = 3 - 2
-15b = 1
b = \( \frac{1}{-15} \)
b = -\(\frac{1}{15}\)

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(7²) + 2π(7 x 5)
sa = 2π(49) + 2π(35)
sa = (2 x 49)π + (2 x 35)π
sa = 98π + 70π
sa = 168π

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 31° - 66° = 83°

So, d° = 66° + 83° = 149°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 31° = 149°