If 3x + 5y = 9 and 5x + 3y = 7, then what is the value of x + y
a) 2
b) 16
C) 9
d) 7
Answers
Step-by-step explanation:
Two equations are given as below:
3x + 5y = 9 …Eq. 1
5x + 3y = 7 …Eq..2
In order to solve, multiplying Eq…1 with 5 and Eq..2 with 3
15x + 25y = 45
15x = 45 - 25y…Eq..3
Now substituting value of 15x from Eq..3 to Eq..4 as following
15x + 9y = 21…Eq…4
45 - 25y + 9y = 21
—16y = 21 - 45
--16y = —24
y = 24/16
y = 3/2
Substituting the value of y in Eq..1
3x + 5 (3/2) = 9
3x + 15/2 = 9
3x = 9 – 15/2
3x = (18 - 15)/2
3x = 3/2
x = 3/2 × 1/3
x =1/2
Now calculating the value of x + y
x + y = 3/2 + 1/2
x + y = 4/2
x + y = 2
Two equations are given as below:
3x + 5y = 9 …Eq. 1
5x + 3y = 7 …Eq..2
In order to solve, multiplying Eq…1 with 5 and Eq..2 with 3
15x + 25y = 45
15x = 45 - 25y…Eq..3
Now substituting value of 15x from Eq..3 to Eq..4 as following
15x + 9y = 21…Eq…4
45 - 25y + 9y = 21
—16y = 21 - 45
--16y = —24
y = 24/16
y = 3/2
Substituting the value of y in Eq..1
3x + 5 (3/2) = 9
3x + 15/2 = 9
3x = 9 – 15/2
3x = (18 - 15)/2
3x = 3/2
x = 3/2 × 1/3
x =1/2
Now calculating the value of x + y
x + y = 3/2 + 1/2
x + y = 4/2
x + y = 2
Answer the value of x + y is 2
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