Let's denote the sales for the previous Saturday as $x.
According to the problem, the sales for last Sunday were an increase of 6.5% over the sales for the previous Saturday.
So, we can set up the equation:
x + 6.5%x = $1,278
To solve this equation, we first convert the percentage to a decimal by dividing by 100:
x + 0.065x = $1,278
Combining like terms:
1.065x = $1,278
To isolate x, we divide both sides of the equation by 1.065:
x = 1278 / 1.065
Calculating this division:
x ≈ 1200
Therefore, Sally's sales for the previous Saturday were approximately $1,199.06.
Answer: 1200