Answer: 75

Let’s solve it step by step.

We are given:

• A + B = 40
• A − B = 10

Add the two equations together:$$(A + B) + (A – B) = 40 + 10$$(A+B)+(A−B)=40+10 $$2A = 50$$2A=50 $$A = 25$$A=25

Now calculate 3A:$$3A = 3 \times 25 = 75$$3A=3×25=75

✅ Final Answer: 75