Question

Solve by the following systems
by Substitution method or Elimination method


0.4x + 0.3y = 1.7

0.7x - 0.2y = 0.8

Class 10

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Answer 1

Here equation one
4/10*x+3/10*y=17/10
4x+3y=17
And equation two
7/10*x-2/10*y=8/10
7x-2y=8
2y=7x-8
y=7x-8/2
Substituting the value of y in equation one
4x+3(7x-8/2)=17
8x+21x-24=34
29x=58
x=2
And
y=7(2)-8/2
=14-8/2
=6/2
=3

Answer 2

Hy there,
From equation 1, we have, 0.4x=1.7-0.3y
Implies x=1.7-0.3y/0.4
Substituting the value of x in Eq 2,
0.7(1.7-0.3y/0.4)-0.2y=0.8
Implies (1.19-0.21y)/0.4-0.2y=0.8
Implies 1.19-0.21y-0.08y/0.4=0.8
Implies 1.19-0.21y-0.08y=0.8*0.4
1.19-0.21y-0.08y=0.32
1.19-0.32=0.21y+0.08y
0.87=0.29y
Implies y=0.87/0.29
Implies y=3
Finding x,
0.7x-0.2(3)=0.8
0.7x-0.6=0.8
0.7x=0.8+0.6
0.7x=1.4
Implies x=1.4/0.7
Implies x=2
Hope it helps.
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