Mark was unwell for 3 months, during which he lost 10 pounds per month. If his final weight was 70 pounds, what was his initial weight?
Since Mark was losing 10 pounds each month, in 3 months he lost 10 * 3 = <<10*3=30>>30 pounds.
Adding the weight lost to the final weight gives an initial weight of 70 + 30 = <<70+30=100>>100 pounds.
Mark's initial weight was 100 pounds.
#### 100