The aveage temperature of Monday, Tuesday and Wednesday was `40^(@)C` . The average temperature of Tuesday, Wednesday and Thursday was ` 41^(@) C` . If the temperature on Thursday was ` 42^(@)C` what was the temperature on Monday ?

Explanation

Sum of temperature on Monday, Tuesday and Wednesday
= `(40xx 3) ^(@)C = 120^(@) C`
Sum of temperatures on Tuesday, Wednesday and Thursday
`=( 41xx 3 )^(@)C = 123^(@) C`
Temperature on Thusday = `42^(@) C`
the temperature on Monday = ` (120 + 42 -123)^(@) C =39^(@)C`
[ by {(i) +(iii) -(ii)}]
Hence, the temperature on Monday was `39^(@)C`