Answer:
30 envelopes
Explanation:
If the Cost of 135 envelopes is Rs 45, then;
135 envelopes = Rs. 45
To get the amount of envelopes Rs. 10 can buy, we can write;
x = Rs. 10
Divide both expressions
135/x = 45/10
45x = 135 * 10
45x = 1350
x = 1350/45
x = 30
Hence Rs. 10 can purchase 30 envelopes