Type the correct answer in the box. Use numerals instead of words. If necessary, use / for the fraction bar. AB is parallel to CD, and EF is perpendicular to AB.
The number of 90° angles formed by the intersections of EF and the two parallel lines AB and CD is

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?