(begin{array}{l} ,left( {525 – 725} right)x = 645 + left( { – 15 – 30} right) + 200\,,,,, – 200x = 645 + left( { – 45} right) + 200\,,,,, – 200x = 600 + 200\,,,,, – 200x = 800\,,,,,,,,,,,,,,,,,,x = 800:left( { – 200} right)\,,,,,,,,,,,,,,,,,,x = – 4end{array})