Obtuse triangles are triangles with one obtuse angle and two acute angles. Define obtuse angles as angles over 90 degrees and acute angles as angles less than 90 degrees.
Explanation: if you bring the fractions down as low as possible, the first bag has a 1 in 4 chance of getting a red marble. The 2nd bag can't be brought down anymore because 26 and 7 do not share any common divisors.