Answer:
Sheila have 6 bills
Step-by-step explanation:
Suppose Sheila has x '20' dollar bills, so the total cost of her bill = $20x
Suppose Tamsin has y '10' dollar bills, so the total cost of her bill = $10y
Equation 1
Sheila has a total of $50 more than Tamsin
10y + 50 = 20x
Equation 2
Tamsin has 1 more bill than Sheila.
y = x + 1
Now solve them by putting value of x in equation
10( x + 1 ) + 50 = 20x
10x + 10 + 50 = 20x
60 = 20x - 10x
10x = 60
x = 60/10
x = 6
and
y = 7
