Answer : 4. "1485"
Explanation :

Given :- Two positive numbers differ by 1280 

When the greater number is divided by the smaller number The quotient is 7 and the remainder is 50 

Concept :- Dividend = Quotient × divisor + remainder 

Calculation :- Let greater number = a and Smaller number = b From question, ⇒ a - b = 1280 ....(1) Again from question, ⇒ a = 7b + 50 ....(2) 

Put the value of a from equation (2) into equation (1) ⇒ 7b + 50 - b = 1280 ⇒ 6b = 1280 - 50 ⇒ 6b = 1230 ⇒ b = (1230/6) ⇒ b = 205 

Put the value of b in equation (1) ⇒ a - 205 = 1280 ⇒ a = 1280 + 205 ⇒ a = 1485 ⇒ Greater number = 1485 ∴ Greater number is 1485