$\"\"$

Food bill = $25.

Sales tax = 6%.

Tip=15%.

$\"\"$

$\"\"$ (Substitute 25 for Food bill, 6% for Sales tax and 15% for tip)

$\"\"$ (Write 6% and 15% as a decimals)

$\"\"$ (Multiply: $\"\"$ )

$\"\"$ (Add: $\"\"$ ) $\"\"$

Total cost is $30.25.