Answer: $10
Step-by-step explanation:
Given
Robin and his four friends bought tickets for [tex]\$12[/tex] each
If each one of them bought a calculator then the total spendings are [tex]\$110[/tex]
Suppose the cost of each calculator is [tex]\$\ x[/tex]
Cost per person is given by [tex]x+\$12[/tex]
For the group, it is [tex]5(x+12)[/tex]
Equate this to total spendings
[tex]\Rightarrow 5(x+12)=110\\\Rightarrow x+12=22\\\Rightarrow x=\$\ 10[/tex]
thus, the cost of each calculator is [tex]\$ 10[/tex]