Question 1202487
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While the answer from tutor @mananth is not correct, there is no need to disparage it, as the other tutor did.  The solution is fine as far as it goes, except for the last careless calculation.  And it doesn't complete the problem....<br>
Without repeating the work that tutor @mananth shows....
x = 25
y = 781.25/25 = 31.25<br>
The dimensions of the printed area are 25 by 31.25 cm.<br>
The area of the whole poster, with margins 4 cm on the sides and 5 cm on top and bottom, is then either 35 by 39.25 cm or 33 by 41.25 cm.<br>
By a general principle the second option gives the smaller area.<br>
ANSWER: 33 by 41.25 cm<br>