If the substance being oxidized is in direct contact with the substance being reduced, what will be produced?
a. mass
b. heat energy
c. friction energy
d. potential energy

The correct option is D. When an oxidant and a reductant are in direct contact, a potential energy is generated whose value is determined by the potential differences between the valence electrons in atoms of the participating elements. The oxidant is the species that gains electrons and is reduced in the process while the reductant is the specie that loses electrons and is oxidized in the process. 

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer