Juan bought 4.5 lbs for $7.98 per lb
This implies that 1 lb is sold at the rate of $7.98
1 lb -------- $7.98
4.5lb ------ $x
Introduce cross multiplication
1 * x = 7.98 x 4.5
x = $35.91
Therefore, 4.5lbs is sold at the rate of $35.91
The tax sales is 6%
Total amount = original price + 6% of original price
Total amount = 35.91 + 6/100 x 35.91
= 35.91 + 0.06 x 35.91
= 35.91 + 2.1546
= $38.0646
The total amount Juan paid is $38.0646