a. 13 oranges = 1 papaya + 2 mangoes
b. 1 papaya = 4 oranges + 1 mango
.....so when 1 papaya in a. is changed by the value of b.
a. 13 oranges = 4 oranges + 1 mango + 2 mangoes
.....by addition principle of equality
a. 13 oranges - 4 oranges = 4 oranges - 4 oranges + 1 mango + 2 mangoes
a. 9 oranges = 3 mangoes or 3 oranges = 1 mango
.....so when b. is changed by the value of 1 mango = 3 oranges
b. 1 papaya = 4 oranges + 3 oranges
b. 1 papaya = 7 oranges
Therefore, 1 papaya is equal to 7 oranges