Abalanced chemical reaction obeys the law
a) ideal gases.
b) definite proportions.
c) conservation of matter.
d) conservation of energy.

C

Explanation:   It obeys the law of conservation of matter because you are putting the same amount of matter on each side of the equation.

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