Dear Student,
(2,3) and (4,0) lie on the line ax + by = 7
Therefore, (2,3) and (4,0) soud satisfy the equation ax + by = 7
Substituting (2,3) in ax + by = 7 : 2a + 3b = 7 ..[1]
Substituting (4,0) in ax + by = 7 : 4a + 0b = 7
or 4a = 7
Substituting the value of a in [1] :
Regards