Cost of the food = Rs. 350
Extra 5% GST is equally shared by Central and State Governments at 2.5% each
∴ CGST = SGST = 350 x \(\frac { 2.5 }{ 100 } \) = Rs. 8.75 

Let the marked price be Rs x.
Now, x + \(\frac { 18x }{ 100 } \) = 10502
\(\frac { 118x }{ 100 } \) = 10502
∴ Marked price, x = Rs. 8900.
GST at 18% = 8900 x \(\frac { 18 }{ 100 } \)
= Rs. 10502 – Rs. 8900
= Rs.1602

Let the number of eggs bought by her be x.
Then, Cost Price = \(\frac { 18 }{ 4 } \times x= \frac { 9x }{ 2 } \)
Selling Price = Rs.\(\frac { 24 }{ 5 } \times x=\frac { 24x }{ 5 } \)
∴ Gain = S.P – C.P = \( \frac { 24x }{ 5 } -\frac { 9x }{ 2 } \)
= \(\frac { 48x-45x }{ 10 } =\frac { 3x }{ 10 } \)
Given, gain = Rs. 90
That is,\(\frac { 3x }{ 10 } \) = Rs. 90
∴ x = \(\frac { 90\times 10 }{ 3 } \) = 300

Let the marked price of an article be Rs. 100.
First discount of 25% = 100 x \(\frac { 25 }{ 100 } \)= Rs. 25
∴ Price aft er fi rst discount = 100 − 25 = Rs. 75.
Second discount of 20% = 75 ×\(\frac { 20 }{ 100 } \) = Rs. 25.
∴ Price aft er second discount = 75 − 15 = Rs. 60.
Net selling price = Rs. 60.
∴ Single discount equivalent to two given successive discounts = (100-60)% = 40%.

Let the C.P of one strawberry box be Rs.  x.
Then C.P of 20 strawberry boxes = 20 x and
S.P of 20 strawberry boxes = C.P of 16 strawberry boxes = 16 x
Thus, S.P < C.P, hence there is a loss.
Loss = C.P –S.P = 20 x − 16 x = 4 x
∴ Loss % =\(\left( \frac { Loss }{ C.P } \times 100 \right) \)%
=\(\left( \frac { 4x }{ 20x } \times 100 \right) \)%
= 20 %