**Ans . **

Rs. 180

**Explanation :**P.W=100 x Amount /[100 + (R x T)]

=Rs.100 x 930/100+ (8x3)

= (100x930)/124= Rs. 750,

T.D. = (Amount) - (P.W.) = Rs. (930 - 750) = Rs. 180.

**Ans . **

Rs. 6000

**Explanation :**Let amount be Rs. x.

Then,x*R*T/100 + (R x T)

=T.D.=>x*12*(3/ 4)/[100+[12*3/4]]=540

x= 540x109 = Rs.6540

Amount - Rs. 6540. P.W. = Rs. (6540 - 540) - Rs. 6000..

**Ans . **

16 2/3%.

**Explanation :**T.D. = Rs. 250 and S.I. = Rs. 375.

Sum due =S.I. xT.D./ S.I. -T.D.=375x250/375- 250=Rs.750.

Rate=[100*375/750*3]%=16 2/3%.

**Ans . **

Rs. 6800

**Explanation :**Let the sum be Rs. x. Then,

T.D. = (x*25/2*1/2)/(100+(25/2*1/2))=x*25/4*4/425=x/17

S.I=x*25/2*1/2*1/100=x/16

x/16-x/17=25 =>17x-16x=25*16*17 =>x=6800

Hence, sum due = Rs. 6800..

**Ans . **

Rs. 3600

**Explanation :**Let the sum be Rs. x. Then,

[x/2+(x/2*100)/100+(25/2*2)]-[(x*100)/(100+25/2*1]=40

=>x/2+2x/5-8x/9=40=>x=3600

Amount of the bill - Rs. 3600