#### Explanation:

let say A = ball, B =bat and C = base.
we can conclude as,

$10 A + 3 B + 2 C = 99$ $\to i$
$4 A + 8 B + 2 C = 78$$\to 2 A + 4 B + C = 39$$\to i i$
$2 A + 3 B + C = 33.60$$\to i i i$

we use silmutaneous equation to solve
$i i - i i i$
B = $5.30 $5 \cdot i i i - i$$12 B + 3 C = 69$, plug in B =5.30 in this equation. $12 \left(5.30\right) + 3 C = 69$$3 C = 5.40$C =$1.80

Plug in B and C in any equations above.eg $i i i$
$2 A + 3 \left(5.30\right) + 1.80 = 33.60$
$2 A = 33.60 - 15.90 - 1.80$
$2 A = 15.90$
A= $7.95 therefore A + B + C =$7.95 + $5.30 +$1.80 = \$15.05#