This question was previously asked in

DSSSB LDC Official Paper 3 (Held on : 25 Aug 2019 Shift 1)

Option 3 : 20 percent

__Shortcut Trick__

Let the M.P of the gadget be Rs.100

C.P = 100 × (100 - 25)% = Rs. 75

S.P = 100 × (100 - 10)% = Rs. 90

Profit% = [(90 - 75)/75] × 100%

**Profit% = 20%**

__Alternate Method__

**Given:**

A gadget was bought at a 25% discount on MRP

A gadget was sold at 10% discount on MRP

**Formula used:**

Profit% = {(SP - CP}/CP} × 100

where,

SP = Selling Price, CP = Cost Price

**Calculations:**

Let the marked price be y

According to the question, we have

When an article is sold at 10% discount on MRP

⇒ SP = {(100 - 10)/100} × y

⇒ SP = 0.9y

When article is bought at 25% discount on MRP

⇒ CP = {(100 - 25)/100} × y

⇒ CP = 0.75y

Profit Percentage is

⇒ Profit% = {(SP - CP)/CP} × 100

⇒ Profit% = {(0.9y - 0.75y)/0.75y} × 100

⇒ Profit% = (0.15y/0.75y) × 100

⇒ Profit% = 100/5

⇒ Profit% = 20%

**∴ The profit percentage is 20%.**