14 . The cost of a mobile phone is pounds The cost of a television is y pounds
When both prices are increased by £40, the ratio for the cost of the mobile phone to the cost of the television is 15:22
When both prices are decreased by £100, the ratio for the cost of the mobile phone to the cost of the television is 8:15
Find the values of x and y

x= 260, y= 400

Step-by-step explanation:

Cost of mobile phone= x pounds

Cost of television= y pounds

When both prices are increased by £40,

cost of mobile phone= £(x +40)

cost of television= £(y +40)

Cross multiply:

15(y +40)= 22(x +40)

Expand:

15y +600= 22x +880

-600 on both sides:

15y= 22x +280 -----(1)

When both prices decreased by £100,

cost of mobile phone= £(x -100)

cost of television= £(y -100)

Cross multiply:

15(x -100)= 8(y -100)

15x -1500= 8y -800 (expand)

15x= 8y -800 +1500 (+1500 on both sides)

15x= 8y +700 (simplify)

-----(2)

Subst. (2) into (1):

Expand:

Subst. y=400 into (2):

use substitution to solve each system of equations. y = x + 5 3x + y = 25 62/87,21 y = x + 5 3x + y = 25 substitute x + 5 for y in the second equation. substitute the solution for x into either equation to find y. the solution is (5, 10)

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