The correct answer for this question is this one:
x + y = 1400 (1)
0.02x + 0.03y = 1400-1364. (2)
Simplify:
x + y = 1400 (1')
0.02x + 0.03y = 36. (2')
Multiply the first eq. by 2.
Multiply the second eq. by 100.
You will get
2x + y = 2800, (1'')
2x + 3y = 3600. (2'')
Subtract eq. ('1'') from the eq. (2'').
You will get
2y = 800.
y = 400
x + y = 1400 (1)
x + 400 = 1400
x = 1000
Hope this helps answer your question and have a nice day ahead.