An easy question all wrong or or no-work answers will be reported.

7x-3y=20
5x+3y=16

solve using two different methods(substitution/elimination) and explain which method you found to be more efficient.

Elimination:

7x - 3y = 20
5x + 3y = 16
(add)
12x = 36
÷ 12
x = 3

(5 × 3) + 3y = 16
15 + 3y = 16
- 15
3y = 1
÷ 3
y = 1/3

Substitution:

5x + 3y = 16
- 3y
5x = 16 - 3y
÷ 5
x = 3.2 - 0.6y

5(3.2 - 0.6y) + 3y = 16
16 - 3y + 3y = 16
16  = 16
- 16
6y = 0
÷ 6
y = 0

Sorry the substitution messed up for some reason, I'll fix it after I've answered the other question