When the mission began, the value of the peso (old) was $12.49 pesos to one dollar. It enabled missionaries to afford life quite easily. The average cost for a month was usually around $125.00 US dollars. Most apartments had a maid that did the cooking, cleaning, washing and shopping.
Even in 1975, the bills shown here were outdated. The 5 and 10 peso notes were soon replaced by coins. The 10 peso coin was octagon shaped. The 20 centavo coins, solid copper, were also soon replaced by much small coins.
Before long the peso was devalued against the dollar and missionaries received up to $30 pesos to the dollar and we all went shopping for souvenirs. It was always easy to tell if the exchange rate was about to change by the big wigs at the bank changing their money to the direction that would best benefit them.
Since the days of the mission runaway inflation caused Mexico to cancel all the old currency in issue new pesos. All our old bills and coins have more collectors' value than they are worth at the bank now.