Answer:
1 Roll = $2.50
1 Battery = $1.50
Step-by-step explanation:
From the question we know that,
8 Rolls + 2 Batteries = $23, and
6 Rolls + 2 Batteries = $18
We can subtract the two equations to obtain a third equation,
(8 Rolls + 2 Batteries) - (6 Rolls + 2 Batteries) = $23 - $18
(8 - 6) Rolls + (2 - 2) Batteries = $23 - $18
2 Rolls = $5
Divide RHS and LHS by 2, to obtain the cost of a roll,
2 Rolls / 2 = $5 / 2
1 Roll = $2.50
If one roll costs $2.50 then 6 rolls cost $15,
6 x $2.50 = $15
We plug in this value into the second equation,
$15 + 2 Batteries = $18
Subtract both sides by $15,
$15 + 2 Batteries - $15 = $18 - $15
2 Batteries = $3
Divide RHS and LHS by 2 to obtain the final answer,
2 Batteries / 2 = $3 / 2
1 Battery = $1.50
