Evaluate an equation by substitution

The video tutorial explains how to solve for the variable b in the equation a + b + c = 180, where b = 3a and c = 5a. The teacher demonstrates using substitution to replace b and c with expressions in terms of a, simplifying the equation to a single variable. By combining like terms, the equation becomes 9a = 180, which is solved to find a = 20. Finally, the value of b is calculated as 3 times a, resulting in b = 60.

What is the initial equation given in the problem?

• a + b = 180

• b + c = 180

• a + c = 180

• a + b + c = 180

What substitution is made for b in the equation?

• b is replaced with 4a

• b is replaced with 2a

• b is replaced with 3a

• b is replaced with 5a

After substitution, what is the simplified equation?

• 6a = 180

• 8a = 180

• 7a = 180

• 9a = 180

What is the value of a after solving the equation?

• 25

• 20

• 15

• 30

What is the final value of b?

• 65

• 60

• 55

• 50