cheese cake = c
chocalate marble = m
Shayna
 c + 4m = 81
Jacob
 4c + 2m = 58
Solving by Elimination
 c + 4m = 81
 -8c - 4m = -116
 -7c = -35
 c = -35/-7
 c = 5
Find m
 5 + 4m = 81
 4m = 81 - 5
 4m = 76
 m = 76/4
 m = 19
The cost of a cheesecake = $5
The cost of a marble cheesecake = $19