Answer:
$5
Step-by-step explanation:
Use simultaneous equations to solve this.
Hamburger = H, Soda = S
Eqn. 1: 2H + 1S = $20 - $1
Eqn. 2: 1H + 2S = $20 - $3
From Eqn. 2:
1H + 2S = $17
1H = $17 - 2S (Eqn. 3)
Substitute Eqn. 3 into Eqn. 1:
2H + 1S = $19
2($17 - 2S) + 1S = $19
$34 - 4S + 1S = $19
Rearrange it to put S on one side, and the $ on the other side:
$34 - $19 = 3S
$15 = 3S
S = $15/3
S = $5
