Step-by-step explanation:
An exponential function has the form:
y = a · b^x
Are you sure you copied the problem correctly? Perhaps instead of minus, you meant multiplication:
f(x) = 620 · 7.8^x
If so, then a = 620 and b = 7.8.
Answer:
Step-by-step explanation:
Let 'x' be the original price.
x + 39% of x = 197.38
x + 0.39 x = 197.38
1.39x = 197.38
x = 197.38/ 1.39
x = 142