The ratio of David’s monthly income to Joe’s monthly income is 3:4 while the ratio of David’ s expenditure to Joe’s expenditure is 5:7. If both David and Joe save ₹3000 every month, find the following. David’s monthly income is ₹ . David’s monthly expenditure is ₹ . Joe’s monthly income is ₹ . Joe’s monthly expenditure is ₹ .
Answers
Answer:-
Given:
Ratio of monthly incomes of David and Joe = 3 : 4
Let their incomes be 3x , 4x.
And,
Ratio of their monthly expenditures = 5 : 7
Hence,
Monthly expenditures of David and Joe are 5y , 7y.
Their monthly savings are Rs. 3000.
We know that,
Savings = Income - Expenditures
Hence,
Savings of David = 3000
→ 3x - 5y = 3000
→ 3x = 3000 + 5y
→ x = (3000 + 5y) / 3 -- equation (1)
Savings of Joe = 3000
→ 4x - 7y = 3000
Substitute the value of "x" from equation (1).
→ 4 * (3000 + 5y)/3 - 7y = 3000
→ [ 4 (3000 + 5y) - 21y ] / 3 = 3000
On cross multiplication we get,
→ 12000 + 20y - 21y = 3 * 3000
→ 12000 - 9000 = y
→ y = 3000
Substitute the value of "y" in equation (1).
→ x = (3000 + 5y)/3
→ x = (3000 + 5*3000) / 3
→ x = (3000 + 15000) / 3
→ x = 18000/3
→ x = 6000
Hence,
• David's monthly income = 3x = 3*6000 = Rs. 18000
• Joe's monthly income = 4x = 4*6000 = Rs. 24000
• David's monthly expenditures = 5y = 5*3000 = Rs. 15000
• Joe's monthly expenditures = 7y = 7*3000 = Rs. 21000