Answer:
$350
Step-by-step explanation:
3 lawns --------------> $105
find unit rate:
1 lawn -------------> $105 ÷ 3 = $35 per lawn
10 lawns --------> $35 per lawn x 10 lawns = $350
Using Gauss's method
Total number of terms = [15-(-129)]/4+1=36+1=37
Add
S=15+11+7+....-125-129
S=-129-125-...+7+11+15
--------------------------------
2S=-114-114-114...(37 times)
=>
sum=S=(1/2)*(-114)*37=-2109
Using AP, T(n)=15+11+7+....-129
T(n)=19-4n => T(1)=15, T(37)=-129
S(n)=(1/2)(37)(T(1)+T(37)=(1/2)37(15-129)=2109
E represents 90, as it is the greatest number given
