Question 1178154


88,83, 78, 73, 

common difference between consecutive terms is -5
first term a = 88

tn = a + (n-1)*d

t28 = 88+(87)*-5

t28 = -347

Sum of terms = Sn = n/2(2a+(n-1)d) 

S7 = (7/2)(2*88+ 6*-5)

S7 =(7/2) * 146

S7 =511