Question

if 7x 10y =55 and 10x + 7y =64​

Answer 1

Answer:

x = 4.5

y = 2.67

Step-by-step explanation:

7x - 10y = 5

10x + 7y = 64

Now, multiply 1st equation by 10 and 2nd equation by 7..

70x - 100y = 50

70x + 49y = 448

Subtracting both..

$(70x - 100y) - (70x + 49y) = 50 - 448 \\ 70x - 100y - 70x - 49y = 50 - 448 \\ - 100y - 49y = 50 - 448 \\ - 149y = 398 \\ y = 2.67$

Ti find x:

$7x - (10\times 2.67) = 5 \\ 7x - 26.7 = 5 \\ 7x = 5 + 26.7 \\ 7x = 31.5 \\ x = \frac{31.5}{7} = 4.5$