Activity - 4 Calculate confidently If a = 2, b = 5, c = 3 Find: 1. a+b = ?, 2. 3c = ?, 3. b-a = ?, 4. 4a+c = ?

Substitute the given values into the expression:

$$a+b = 2+5 = 7$$

The student's answer of 7 is correct.

Substitute the given value into the expression:

$$3c = 3 \times 3 = 9$$

The student's answer of 9 is correct.

Substitute the given values into the expression:

$$b-a = 5-2 = 3$$

The student's answer of 3 is correct.

Substitute the given values into the expression:

$$4a+c = 4 \times 2 + 3$$

Perform the multiplication first:

$$4 \times 2 + 3 = 8 + 3 = 11$$

The student's answer of 10 is incorrect. The correct answer is 11.

Here are the evaluated expressions:

1. $a+b = \boxed{7}$ (Student's answer: Correct)
2. $3c = \boxed{9}$ (Student's answer: Correct)
3. $b-a = \boxed{3}$ (Student's answer: Correct)
4. $4a+c = \boxed{11}$ (Student's answer: Incorrect, should be 11)