Answer:
total length= 4 ¹/₂ meters
Explanation:
If each board had 9/10 of a meter long (0,9 m or 90 cm long) , the total length of the boards was the sum of all each board's length, that is 5 times 9/10 of a meter. Mathematically
total length = 5 boards * 9/10 meters/board = 5*9/10 meters = 45/10 meters
45/10 meters can be simplified dividing by the common factor 5
45/10 = (9*5)/(2*5) = 9/2
then dividing 9 over 2 → equals 4 with rest = 1 (that is 9 = 4*2 +1)
therefore
9/2 = 4 ¹/₂ , 4=result of division , 1= rest , 2=denominator of the fraction
total length=9/2 meters = 4 ¹/₂ meters