147., two successive discount of 20% and 75% is equivalent to a single discount of:

if two doscounts x and y are given, then

total discount= (x+y-xy/100)%

by the question,

x=20%

y=75%

hence total discount= (20+75-20×75/100)%

=(95-1500/100)%

=(95-15)%

=80%

answer: a.letter a . . letter "correct answer"

b.letter c . . letter b "not b'

c.letter a . . letter b

d.letter b . . letter a

explanation:

1."lessen the worth of ."

2."increase the worth of."

3." beyond the worth of."

4."against the worth of ."