Answer:
z = 60
Step-by-step explanation:
z/3 = 20. (Multiply both sides by 3 to isolate ‘z’)
20 • 3 = 60
78.00 = 59.99+0.10x
10.01=0.10x
x= 180.1 so she can send 180 texts plus the 100 free ones for a total of 280 texts
double check: 180 x 0.10 = 18.00 + 59.99 = 77.99