You have to subtract the low from the high
20-(-25)
20+25
45
Answer: 
Step-by-step explanation:

Total cost = 15*14 ( 0.89 + 2.99 ) + 2(15 + 14) 0.19 = $825.82
Answer + Step-by-step explanation:
1) D be the symmetric of B with respect to C then CD = BC
A the symmetric of C with respect to B then AB = BC
We obtain :
CD = BC
AB = BC
Then AB = CD
2) m∠SBA = 180 - SBC = 180 - SCB = m∠SCD
3) we have :
BA = CD
BS = CS
m∠SBA = m∠SCD
Then
the triangles SBA and SCD are congruent
4)
the triangles SBA and SCD are congruent Then SA = SD
Therefore SAD is an isosceles triangle.