If a*b means a + b + ab/10. Find the value of [(-5)*2]*4.

A)15.2
B)-13.8
C)-1.6
D)0

1 answer

working inside the [] first, we have
(-5)*2 = (-5)+(2) + (-5)(2)/10 = -5+2-1 = -4
then
(-4)*4 = (-4)+(4)+(-4)(4)/10 = -4+4-16/10 = -8/5